A dial tone is a telephony signal that is typically sent on a telephone line by a telephone exchange as an incoming signal to a terminating device, such as a telephone, when an off-hook condition is detected on the telephone line. An off-hook condition is the state of a telephone line that allows dialing and transmission and/or other activity such as answering an incoming telephone call and generally occurs when a terminating device, such as a telephone, is selected for use such as by lifting a handset off of a base, pressing a speakerphone button, or pressing a talk button, for example. The dial tone indicates that the exchange is working and is ready to accept an outgoing telephone call initiated by a terminating device such as a telephone. The dial tone typically terminates when the first dialed digit from the telephone is recognized by the exchange. Therefore, when a human user hears a dial tone on a telephone line, the user can generally begin dialing a telephone number with confidence that the telephone line is available for initiation of an outgoing telephone call.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described herein may be practiced.